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Una nueva especie de bagre de caverna, género Trichomycterus (Siluriformes: Trichomycteridae), del sistema río Magdalena, cordillera Oriental, Colombia PDF

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Preview Una nueva especie de bagre de caverna, género Trichomycterus (Siluriformes: Trichomycteridae), del sistema río Magdalena, cordillera Oriental, Colombia

Castellanos-Morales A new species of cave catfish, genus Trichomycterus (Siluriformes: Trichomycteridae), from the Magdalena River system, Cordillera Oriental, Colombia A new species of cave catfish, genus Trichomycterus (Siluriformes: Trichomycteridae), from the Magdalena River system, Cordillera Oriental, Colombia Una nueva especie de bagre de caverna, género Trichomycterus (Siluriformes: Trichomycteridae), del sistema río Magdalena, cordillera Oriental, Colombia César A. Castellanos-Morales Abstract A new species of troglomorphic catfish is described from de Gedania Cave, located in the middle Suárez River drainage, Magdalena River system, Colombia. The new species can be distinguished from its congeners by the combination of the following characters: reduction or loss of the cornea, reduction of eyes and skin pigmentation, very long nasal and maxillary barbels (maximum of 160% and 135% of HL, respectively), nine branched pectoral-fin rays, first unbranched ray of the pectoral fin prolonged as a long filament, reaching 80% of pectoral-fin length, anterior cranial fontanel connected with the posterior fontanel through an opening of variable length and width, first dorsal- fin pterygiophore inserted between neural spines of free vertebra 13-14 and free vertebrae 33-34. The presence of troglomorphisms such as regression of the eyes, reduction of skin pigmentation and long barbels suggest the troglobitic status of this species. A comparative analysis with other species of Trichomycterus from epigean and hypogean environments is presented. Keywords. Andean region. Subterranean habitat. Systematics. Taxonomy. Troglobite. Resumen Una nueva especies de bagre troglomorfo es descrito de la cueva de Gedania, cuenca media del río Suárez, sistema río Magdalena, Colombia. La nueva especie puede distinguirse de sus congéneres por la combinación de los caracteres de reducción o pérdida de la córnea, reducción de ojos y pigmentación de la piel, barbillas nasales y maxilares muy largas (máximo 160 % y 135 % de LC respectivamente), nueve radios ramificados de la aleta pectoral, primer radio simple de la aleta pectoral prolongado como un filamento largo, alcanzando 80 % de la longitud de la aleta pectoral, fontanela craneal anterior conectada con la fontanela posterior por una apertura de amplitud y longitud variable, primer pterigioforo de la aleta dorsal insertado entre la espina neural de la vértebra libre 13-14 y 33-34 vertebras libres. La presencia de características troglomorficas como la regresión de ojos y reducción de la pigmentación, así como barbillas largas sugieren el estatus troglobítico de la especie. Se presenta un análisis comparativo con otras especies de Trichomycterus de ambientes epigeos e hipogeos. Palabras clave. Hábitat subterráneo. Región andina. Sistemática. Taxonomía. Troglobio. 117 Biota ColomBiana 19 (Sup. 1) - 2018 DOI: 10.21068/c2018.v19s1a10 Castellanos-Morales Introduction Trichomycteridae is a family of Neotropical T. dali Rizzato, Costa-Jr, Trajano and Bichuette, freshwater catfishes widely distributed in Central 2011 (Saracura y Buraco das Abelhas Caves), and and South America, on both sides of the Andes T. rubbioli Bichuette y Rrizzato, 2012 (Lapa dos mountain range from sea level to 4500 m a.s.l (de Peixes Cave), and 2 undescribed forms (Bichuette Pinna & Wosiacki, 2003). Currently, the family & Rizzato, 2012); 2 species are known from represents one of the most species-rich groups Venezuela: T. spelaeus DoNascimiento, Villarreal of Siluriformes with at least 300 valid species & Provenzano, 2001 (Punto Fijo Cave) and 1 and 41 valid genera (Eschmeyer et al., 2017). Its undescribed species from El Guácharo Cave, a monophyly is well corroborated and its most species previously considered to be a hypogean conspicuous synapomorphies are based on its population of T. conradi (DoNascimiento, 2005); highly specialized opercular-interopercular finally 1 species is found in Bolivia: Trichomycterus apparatus (de Pinna, 1998; Datovo & Bockmann, chaberti Durand, 1968 (Umayalanta Cave). These 2010). The genus Trichomycterus is the most diverse species (except T. sketi) show troglomorphic within the Trichomycteridae, containing over 170 characteristics (e.g. reduced eyes or not visible valid species (Eschmeyer et al., 2017). In Colombia, externally and, pigmentation reduction), indicating the genus is represented by 41 species, of which a troglobitic condition. This paper describes a eight have been recently described: Trichomycterus new subterra-nean, troglomorphic Trichomycterus steindachneri (DoNascimiento et al., 2014), T. nietoi species from the middle Suárez River drainage, (Ardila-Rodríguez, 2014), T. tetuanensis (García- Magdalena Basin, La Paz municipality, Melo et al., 2016) and T. arhuaco, T. garciamarquezi, southwestern Santander Department, in the T. kankuamo, T. manaurensis, T. montesi (Ardila- Andean region of Colombia. Rodríguez, 2016). Trans-Andean drainages (Magdalena, Cauca, San Juan, and Sinú basins) Materials and methods have the largest number of species (Castellanos- Morales & Galvis, 2012). Measurements were taken point-to-point with dial calipers from the left side of each specimen Trichomycterid catfishes are among the most with the aid of a stereomicroscope. Methodology successful colonizers of subterranean habitats and terminology for measurements and counts (Castellanos-Morales, 2008), with troglobitic and follow de Pinna (1992), with the addition of troglophilic populations (Mattox et al., 2008), length of first and second pectoral-fin rays, including several troglobitic species in 4 genera, eye diameter and interopercular patch length. Silvinichthys (Argentina), Glaphyropoma (Brazil), Measurements are presented in percentage Ituglanis (Brazil), and Trichomycterus (Bolivia, of standard length (SL) and head length Brazil, Colombia and Venezuela) (Proudlove, (HL). Osteological data and number of 2010). Currently 14 hypogean species of branchiostegal and procurrent rays, vertebrae, Trichomycterus have been reported in South ribs, fin rays, number and position of supporting America; Colombia has the largest number with elements of dorsal and anal fins, and other 6 species: T. sandovali Ardila-Rodríguez, 2006 (Don osteological features were obtained from Juan cave), T. santanderensis Castellanos-Morales, two paratypes cleared and double-stained (C&S) 2007 (El Puente Cave), T. sketi Castellanos-Morales, for bone and cartilage following the method 2010 (Del Indio Cave), and T. uisae Castellanos- of Taylor & Van Dyke (1985). Osteological Morales, 2008 (El Misterio Cave), and at least nomenclature follows Bockmann et al. (2004). 2 additional undescribed species (Castellanos- Vertebral counts include only the free vertebrae Morales et al., 2011, Castellanos-Morales & Galvis, (posterior to the Weberian complex), and 2012); Brazil has 3 species: T. itacarambiensis the compound caudal centrum (PU1+U1) Trajano and de Pinna, 1996 (Olhos d’Água Cave), was counted as one element (Lundberg & 118 Biota ColomBiana 19 (Sup. 1) - 2018 Castellanos-Morales A new species of cave catfish, genus Trichomycterus (Siluriformes: Trichomycteridae), from the Magdalena River system, Cordillera Oriental, Colombia Baskin, 1969). The presence or absence of the Base website from the All Catfish Species cornea was determined by direct observation Inventory (Morris et al., 2006) and the Illustrated throughout light stereo microscope. Color was and online catalog of type specimens from the determined according to the Munsell soil color Instituto de Investigación de Recursos Biológicos chart (M) (1994). Morphological data for other Alexander von Humboldt (DoNascimiento et al., species are based on personal observations, 2016). Institutional abbreviations follow Sabaj literature and available images at the Image (2016). Results Trichomycterus donascimientoi, new species Figure 1. Trichomycterus donascimientoi, CAC-CDMB 224, holotype, 78.0 mm SL, Colombia, Santander department, La Paz municipality, Gedania Cave, Suárez River basin, Magdalena River system. Lateral view of the right side. Scale bar = 1 cm. Holotype. CAC-CDMB 224, 78.0 mm SL, system, César A. Castellanos-M., Fabián Moreno-R Colombia, Departamento de Santander, Municipio & Liliana Toro-M, 15 Dec 2014. La Paz, vereda Casas Blancas, cueva de Gedania, 6 km South of town (06°08’07.9” N 73°35’50.4” W, Paratypes. Collected with the holotype. CAC- elevation 1871 m), near quebrada La Gran Curí, CDMB 225 (4, 55–76.5 mm SL), CAR 780 (2, 34.2 middle Suárez River drainage, Magdalena River – 66.5), IAvH-P 16143 (2, 48.8–68.4 mm SL), ICN– 119 Biota ColomBiana 19 (Sup. 1) - 2018 DOI: 10.21068/c2018.v19s1a10 Castellanos-Morales MHN 21744, (2, 46.4–79.9 mm SL), MLS 1578 (1, cranial fontanel connected to the posterior fontanel 66.4 mm SL) UIS-T-2294 (1, 59.1 mm SL). by an opening of variable length and width except T. uisae (vs. fontanels separated by epiphyseal in Diagnosis. Trichomycterus donascimientoi is readily almost all epigean species). distinguished from hypogean congeners by the presence of 33-34 free vertebrae (vs. 35-36 in T. Trichomycterus donascimientoi can also be itacarambiensis, T. sandovali and T. santanderensis; 35 differentiated from the only other species in T. dali and sketi; 31-32 in T. rubbioli and T. uisae). described from the same geographic area (La Trichomycterus donascimientoi can be distinguished Paz, Santander), T. sketi, by the origin of pelvic from epigean and most hypogean species of the fin slightly posterior to vertical through the dorsal genus by the following combination of characters: fin origin (vs. anterior to dorsal-fin origin). T. reduced skin body pigmentation (except T. donscimientoi has its first dorsal-fin pterygiophore gorgona and hypogean congeners T. chaberti, inserted between the neural spines of free vertebra T. itacarambiensis, T. sandovali, T. santanderensis, 13-14, in T. sketi it is inserted in free vertebra 17- T. spelaeus and T. uisae); reduced eyes, (vs. eyes 18, and first anal-fin pterygiophore is inserted well developed in all epigean species, except T. between hemal spines of free vertebrae 18-19 gorgona, and the hypogean species, T. chaberti, (vs. free vertebra 20-21). Also, Trichomycterus T. itacarambiensis, T. rubbioli, T. santanderensis, T. donascimientoi differs from T. sketi by having 24- sketi and T. uisae ) reduction or loss of the cornea 26 dorsal procurrent caudal-fin rays (vs. 16-18), (vs. well-developed cornea in all epigean species); reduction or loss of the cornea (vs. cornea present) long nasal and maxillary barbels (reaching a and well-developed troglomorphisms (vs. not maximum of 160% and 135% of HL, respectively), developed). except for species with well-developed barbels mostly restricted to subterranean habitats: T. According to Castellanos-Morales et al. (2011), dali, T. rubbioli, T. sandovali, T. santanderensis, the following species of Trichomycterus inhabit the T. spelaeus, T. sketi and T. uisae and, epigean T. Suárez River basin, in the department of Santander, longibarbatus. Trichomycterus donascimientoi is Colombia: T. bogotensis, T. latistriatus, T. sandovali further distinguished from almost all congeners and T. straminius. Trichomycterus donascimientoi (except epigean T. hualco and T. roigi and the differs from T. bogotensis, T. latistriatus and T. cave restricted T. dali, T. rubbioli, T. sandovali straminius by well-developed troglomorphisms and T. sketi) by pectoral-fin ray count reaching 9 (vs. not developed) and nine pectoral-fin branched branched rays (vs. 6–8); and the first ray of the rays (vs. six to eight). Also, T. straminius has a pectoral fin prolonged as a long filament, except rounded caudal-fin edge (vs. obliquely rounded all hypogean Trichomycterus (vs. first pectoral in T. donascimientoi). Trichomycterus bogotensis fin ray not prolonged or variably extended in all and T. latristiatus differ from T. donascimientoi by epigean species). Trichomycterus donascimientoi the dorsal-fin origin anterior to origin of pelvic can be diagnosed from almost all congeners, fin, (vs. at the same level or slightly anterior excluding T. sketi and T. uisae by the caudal fin to the origin of the pelvic-fin). Trichomycterus obliquely rounded, with upper portion of caudal donascimientoi differs from T. sandovali by the fin slightly longer than lower portion (vs. rounded presence of eyes (vs. absence), 33-34 free vertebra or truncate in the remaining trans-Andean species (vs. 35-36) and dorsal-fin origin after the midpoint from Colombia); coloration from homogeneous of the standard length (before the midpoint of the light-red to pale rose, similar to that reported standard length). for troglomorphic species from Colombian cave environments (vs. variably pigmented in epigean Description. Morphometric data presented in trans- Andean species from Colombia and the Table 1. Body elongated, deeper than wide, hypogean T. sketi and T. itacarambiensis); anterior gradually deeper from pectoral region to pelvic-fin 120 Biota ColomBiana 19 (Sup. 1) - 2018 Castellanos-Morales A new species of cave catfish, genus Trichomycterus (Siluriformes: Trichomycteridae), from the Magdalena River system, Cordillera Oriental, Colombia insertion; dorsal profile convex from nape to origin Eyes positioned dorsally on anterior half of head, of dorsal fin; ventral profile slightly straight, dorsal variably reduced in size from well-developed to and ventral profile of caudal peduncle slightly visible externally as small black spots and slightly convex. Thick and pale integument. Head wide, covered by integument continuous with head depressed and triangular in dorsal view; dorsal skin. Reduction or loss of the cornea, from well- profile of head straight, ventral and lateral profile developed in young specimens to absent in large convex; jaw muscles not particularly developed. specimens (66 mm SL or more). Table 1. Morphometric data for holotype (H) and 12 paratypes of Trichomycterus donascimientoi. Standard length (SL) expressed in mm. Measurements 2-10 expressed as percents of SL; Measurements 11 - 19 expressed as percent of head length (HL). M: mean; R: range. H M R Standard length 78.0 - 34.2 - 80.0 Percentage of standard length Total length 116.7 117.8 115.8 - 121.0 Body depth 16.7 16.9 15.5 - 19.5 Predorsal length 56.9 56.9 54.7 - 59.7 Prepelvic length 55.4 57.4 55.9 - 60.5 Preanal length 69.0 70.5 67.6 - 73.5 Caudal peduncle length 22.0 22.2 20.7 - 23.9 Caudal peduncle depth 13.5 13,8 13.3 - 14.6 Dorsal-fin base length 10.6 10.7 9.8 - 12.1 Pelvic-fin base length 2.8 2.7 2.2 - 3.0 Head length 19.3 20.2 19.0 - 22.2 Percentage of head length Head width 105.5 100.9 93.0 - 108.2 Head depth 61.0 58.7 56.0 - 63.2 Mouth width 47.1 39.1 31.7 - 47.1 Eye diameter 1.9 6.7 1.9 - 11.7 Interorbital width 35.6 33.8 31.6 - 36.3 Nasal barbel length 105.5 124.3 104.6 - 160.2 Maxillary barbel length 102.7 107.7 88.5 - 134.9 Rictal barbel length 72.5 73.0 60.7 - 83.8 Interopercular patch length 15.3 17.0 14.6 - 19.4 121 Biota ColomBiana 19 (Sup. 1) - 2018 DOI: 10.21068/c2018.v19s1a10 Castellanos-Morales Mouth subterminal, with corners oriented and, anterior portion of parieto-supraoccipital backwards. Lower lip with conspicuous fleshy bone (Figure 3). Thicked branchial membranes, lateral lobes. Anterior nostril ovoid and slightly united to isthmus anteromedially and forming smaller than posterior one, surrounded by free fold across isthmus. Gill opening wide. slightly raised thick integument, continuous with Branchiostegal rays seven (Figure 4), ray 5 with nasal barbel. Posterior nostril rounded, oriented enlarged distal tip, ray 6 surpasses posteriorly transversally, surrounded anteriorly by laterally- ray 5, with distal portion located under ray 5 folded flap of integument. Teeth conical, slightly and covered by interopercle, ray 7 with a medial straight but curved at the tip, arranged in 3-4 portion of the ray locate under de rays 6 and 5, irregular rows on upper jaw and three rows on reaching ventral margin of opercular patch of lower jaw (Figure 2). Nasal and maxillary barbels surpassing base of pectoral fin. Nasal barbel longer than maxillary barbel. Interopecular patch of odontodes well developed, with 25-29 conical and elongated odontodes, arranged in 4 irregular rows, with large interopercular odontodes on the posterior edge. Opercular patch of odontodes small, with 9-11 conical odontodes arranged in 3 irregular rows. Neurocranium with elongate mesethmoid T-shaped. Anterior fontanel small, triangular in shape, located between frontals at level of infraorbital canal exit. Posterior fontanel long and connected with anterior fontanel through opening of variable length and width. Anterior one-third of posterior fontanel situated between frontal bones Figure 3. Dorsal view of the neurocranium of Trichomycterus donascimientoi. CAC-CDMB 225, 59.1 mm SL. afo, anterior fontanel; i1, infraorbital sensory pore 1; i3, infraorbital sensory pore 3; i10, infraorbital sensory pore 10, i11, infraorbital sensory pore 11; le, lateral ethmoid; me, mesethmoid; pfo, posterior fontanel; pr, preopercular sensory pore; psoc, parieto-supraoccipital; pt, pterotic; ptb, pterotic branch; pttsc, posttemporo-supracleithrum; s1, supraorbital sensory pore 1; s3, supraorbital Figure 2. Left lower jaw in medial view of sensory pore 3; s6, supraorbital sensory pore Trichomycterus donascimientoi, CAC-CDMB 225, 6; so,supraorbital tendon bone; sp+pro+pts, 59.1 mm SL. Abbreviations: AR: anguloarticular sphenotic-prootic-pterosphenoid complex bone; ; CP, coronoid process; DE, dentary. Scale bar = tc, trunk canale; wc, weberian capsule. Scale bar 1 mm. = 2 mm. 122 Biota ColomBiana 19 (Sup. 1) - 2018 Castellanos-Morales A new species of cave catfish, genus Trichomycterus (Siluriformes: Trichomycteridae), from the Magdalena River system, Cordillera Oriental, Colombia odontodes. Urohyal with long, very narrow urogenital opening. Inner margins of pelvic-fin posterior process, broad convex posterior margin, bases slightly separated. Basipterygium with two lateral process with distal margins chipped, long anterior processes narrowing from base to hypobranchial foramen slightly ovoid. Hypohyal distal tip, one or two medial processes and one with depression to which articulates anterior short posterior process. Anal fin similar to dorsal process of urohyal. Head sensory canals with fin, but smaller, with ii,6 rays, its origin at level simple tubes. Sensory pore s1 medially adjacent of last dorsal-fin ray. First anal-fin pterygiophore to anterior nostril. s3 medial to posterior nostril. inserted between hemal spines of vertebrae 18- s6 at level of posterior eye. Infraorbital sensory 19. Caudal-fin edge obliquely rounded. Principal canal with 2 segments, anterior with 2 branches caudal-fin rays 14. Caudal skeleton with neural and pores (i1 and i3) and posterior segment with spine of preural centrum 2 well developed. 2 branches and pores (i10 and i11). Preopercular Hypurals 1 and 2 fused to parhypural, associated canal short, pore above origin of opercular patch with two unbranched rays and seven branched of odontodes. Postotic canal with pore above rays; hypural 3 fused to hypural 4, articulating opercular patch of odontodes. with three branched rays; hypural 5 narrowly separated from hypurals 3+4 for entire length, Pectoral-fin margin rounded with i,9 rays. First associated with one unbranched ray and one ray thin and fragile, prolonged as a long filament. branched ray (Figure 5). Uroneural with slightly Scapulocoracoid with long anteriorly directed rounded distal tip, not fused to hypural 5. Neural process, located close to first pectoral-fin ray base. spine 1 of preural centrum reduced to almost Dorsal fin rounded, located slightly anterior to 25% of uroneural length, rounded tip projected pelvic-fin origin, with ii,6 rays. First dorsal-fin upward. Dorsal procurrent caudal-fin rays 24- 26, pterygiophore inserted between neural spines of and 14-16 ventral procurrent rays. Free vertebrae free vertebra 13-14. Pelvic-fin rays i,4, with a lateral 33-34. Ribs 11-12. Anal and urogenital openings splint. Pelvic-fin origin slightly posterior to vertical closer to anal-fin origin than to pelvic-fin base, through dorsal-fin origin and its edge surpasses totally covered when pelvic fin extended. Figure 4. Left hyoid arch of Trichomycterus Figure 5. Caudal skeleton of Trichomycterus donascimientoi CAC-CDMB 225 59.1 mm SL. donascimientoi, CACCDMB 225, 57 mm SL. HY: Ventral view. Abbreviations: AC, anterior hypurals 1-5; NS 1: neural spines of preural ceratohyal; BR 1 to 7, branchiostegal rays; PC, centrum; PH: parhypural; PU1+U1: complex posterior ceratohyal; UR, urohyal; VH, ventral preural centrum 1+ ural centrum 1; UN: uroneural. hypohyal. Scale bar = 1 mm. Scale bar = 1 mm. 123 Biota ColomBiana 19 (Sup. 1) - 2018 DOI: 10.21068/c2018.v19s1a10 Castellanos-Morales Coloration in live specimens. Body color light- in the Magdalena River system, Department of brown (M 10YR - 5/6). Base of all fins yellow (M Santander, Colombia. 5YR – 6/8 to M 2.5Y – 7/6). Ecological data. The de Gedania Cave (also known Coloration in alcohol. All specimens with ground as del Puya Cave) is located at approximately color pale yellow (M 5Y - 8/4). Base of all fins 6.2 km South from the municipality of La Paz – yellow (M 2.5Y – 7/6). Santander (Figure 6). This region is on the western flank of the Andean Cordillera Oriental, with Distribution. Trichomycterus donascimientoi is lithostratigraphic sedimentary units from the known exclusively from the hipogean environment Cretaceous period grouped in different geologic of the de Gedania Cave, near to Gran Curí River, formations as Rosablanca, Paja, Tablazo, Simit, Figure 6. Map of La Paz, northeastern region of Colombia, showing the geogr aphic position of the de Gedania Cave in the town of Casas Blancas. This is the type locality of Trichomycterus donascimientoi. 124 Biota ColomBiana 19 (Sup. 1) - 2018 Castellanos-Morales A new species of cave catfish, genus Trichomycterus (Siluriformes: Trichomycteridae), from the Magdalena River system, Cordillera Oriental, Colombia and Luna (Castellanos et al., 2015). The entrance agricultural production such as sugar cane, cocoa, of the cave is oriented horizontally 60° NW, and corn and coffee, which use agrochemicals to has a small flow of water that in the period of grow the crops. The deteriorating environmental low rainfalls remains completely dry (Figure 7). conditions near the de Gedania Cave, water The de Gedania cave has three main sections: the bodies inside the cave by infiltration process and first section, here named Tunnel A, has a length of the low population number of T. donascimientoi 156 m. The height vary inside the tunnel from 0.8 m provide some criteria to consider this species at to up to 3.1 m high and 1.2 to 3.1 m wide. Small risk of extinction and a priority in conservation wells are interconnected by reduced descending programs. Also, should the species should be channels along the tunnel. The bottom of each well included in the Red Data Book for Colombian is rocky and contains abundant fine sediment. The freshwater fishes. The de Gedania Cave was second section has a small gallery called Gallery first explored by the Polish Commission 1975, A with an average height of 7 m and 8 m wide. who named it in honor to the Polish city Gdansk The third section, called Gallery B, starts with a (Comisión Polaca, 1977). Other species that inhabit waterfall formed by the infiltration process with the interior of the cave include bats (Carollia 50 m high, from which the last gallery, with about perspicillata), crabs (Neostrengeria charalensis), 90 m long and up to 20 m high is connected. crickets (Phalangopsidae: Phalangopsinae) and Specimens of the new species were collected in the aquatic insects (Gerridae, Hemiptera, Heteroptera, first and second sections of the cave, where the Veliidae and Opiliones (cf. Stygnidae) (pers. obs.)). water temperature was 17.9°C, cave temperature 18.1°C, and water pH was 6.7. Neither stalagmites Etymology. The specific epithet is in honor nor stalactites, or any kind of incrustation, was of Carlos DoNascimiento for his invaluable recorded inside the cave, (Comisión Polaca, orientation in my research about the genus 1977; pers. obs.). The population densities of Trichomycterus. The name is used as an adjective Trichomycterus donascimientoi recorded in three genitive masculine singular. different expeditions were extremely low. The cave is located in an area with livestock and Common name: Lauchas. Figure 7. Type locality of Trichomycterus donascimientoi. A. inside the de Gedania Cave. B. outside of the de Gedania Cave, middle Suárez River basin, Santander, Colombia. 125 Biota ColomBiana 19 (Sup. 1) - 2018 DOI: 10.21068/c2018.v19s1a10 Castellanos-Morales Discussion Troglomorphic species are restricted to sub- of appendages bearing sensorial structures is terranean environments and exhibit, in variable broadly recognized as the most common trait degrees, the following characters: reduction of characterizing troglobites (Hüppop, 2000; Trajano, eyes, reduced skin pigmentation, and relatively 2001). According to Romero & Green (2005) the long barbels (Romero & Paulson, 2001; Trajano, degree of development of some characters (e.g., 2005; Bichuette & Trajano, 2008; Bichuette barbel elongation in hypogean fishes from families & Rizzato, 2012). These characters are very in which barbels are a common characteristic) is distinctive and well developed in Trichomycterus conditioned by their phylogenetic history. The donascimientoi. Three species of Trichomycterus new species Trichomycterus donascimientoi has very restricted to subterranean environments share long barbels, especially the nasal and maxillary the above mentioned features with Trichomycterus barbels, which is a remarkable character that can donascimientoi: T. rubbioli, T. santanderensis, and T. distinguish the species from its epigean congeners uisae. Moreover, T. dali, T. sandovali, and T. spelaeus and other troglomorphic cave catfishes such as are species that share the last two characters cited T. chaberti and T. itacarambiensis, where nasal and above; however, these species differ from T. maxillary barbel length is shorter than 80% and donascimientoi because they lack eyes. 90% of HL, respectively. Trichomycterus donascimientoi exhibits an additio- According to Bockmann & Sazima (2004) the nal feature that could be related to hypogean number of pectoral-fin rays has been considered life: the extension of the first pectoral fin ray as a conservative within Trichomycteridae: long filament which widely surpasses the edge Trichomycterinae. In this sense, García-Melo et of the pectoral fin (reaching 80% of pectoral- al. (2016) showed that the pectoral-fin ray count fin length). This condition is also present in all is a character homoplastically distributed in restricted cave fishes of Trichomycterus. In all trichomycterines, Bullockia and Hatcheria as well as species of the genus the extension of the filament many Trichomycterus species have similar number can vary in length from 50% to 95% of the pectoral- of branched pectoral-fin rays. For this reason, fin length of T. santanderensis (Castellanos-Morales, these authors do not discard the potential of this 2007). A more comprehensive analysis focusing character as informative for several subgroups of on this condition in both epigean and hypogean Trichomycteridae, including the Trichomycterus species of Trichomycterus should be developed in sensu stricto clade. In T. donascimientoi count future studies. of pectoral-fin rays reaches i,9, which has been considered by Bichuette & Rizzato (2012) as a rare Evolution of troglomorphic characters may be condition for the genus. Only three cave species associated with selective pressures which may differ (T sandovali, T sketi and T. dali) and one epigean from cave to cave (Culver et al., 1995). In addition species (T. hualco) share this condition with T. to reduction or loss of some structures, many donascimientoi. Most Trichomycterus species have troglomorphic organisms exhibit enhancement of i,7 pectoral-fin rays, and less commonly i,6 to i,8 others, particularly those associated with chemical pectoral-fin rays. and mechanical sensory systems which are essential for foraging, mating, etc., in the absence The cornea is the anterior, transparent window of vision (Romero & Green, 2005). Some species in the collagenous scleral coat of the eyes that from the genera Trichomycterus and Ituglanis contributes to the structural support of the globe, are exclusively hypogean and have elongated protects the inner eyes from organismal invasion barbels that are more developed than those and unwanted environment changes, and helps observed in epigean congeners. The enlargement control intra and extra ocular pressures (Collirt 126 Biota ColomBiana 19 (Sup. 1) - 2018

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